This invention relates to the conversion of cotton gin waste to a humus-like substance having the properties of improving plant growth while at the same time suppressing or eliminating soil borne plant pathogenic microorganisms, viruses, insects, spider mites, weed seeds and certain organic insecticidal residues, herbicidal residues, chemical plant growth regulators and related agents harmful to plant and animal growth. Historically, suppression or elimination of soil borne pests of plants has been accomplished by means of applying heat to the mass of soil to be cleansed, the application of toxic gases as by fumigation and by the application of toxic chemicals as drenches or powders to the soil or plant growing medium. Many common horticultural plant growing media are formulations of sand, peat moss of various kinds, minerals such as vermiculite and perlite, plant foods, and agents to assist in wetting the mass. All such materials must by law be rendered free of pests by means of approved heat or chemical fumigation or treatment in order to be shipped or sold commercially.
The present art of formulating horticultural plant growing media precludes the use of certain agricultural organic residues because they contain many of the pests plant growers seek to avoid. Additionally, growers have found that if the media are not completely free of plant disease causing agents at the time of planting, a small contamination may spread wildly through the medium and the planting may be lost. For this reason agricultural waste products are commonly destroyed or abandoned in dumps or by other means and their value is lost.
A specific example is that of cotton gin waste. In the humid and irrigated areas of the cotton belt each 500-pound bale of cotton lint generates approximately 150 pounds of waste. A 10,000-bale gin in the Mississippi Delta produces about 800 tons of waste. In previous years this waste was burned in an open refuse burner. The smoke from the burners, unfortunately, contains toxic substances including the combustion products of the pesticidal chemicals and harvest aids, some of which may contain severe poisons such as arsenic. Beginning in 1974 the Environmental Protection Agency prohibited open burning of cotton gin waste. Because the material contains plant pests it cannot legally be moved off the premises of the gin unless certified free of pests by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service. The net result is a large pile of gin waste which is almost impossible to handle after it begins to decay and becomes semi-liquid.
In areas where the crop is harvested with spindle pickers the cotton gin waste normally consists of the following materials:
______________________________________ PHYSICAL CONSTITUENTS Seed (broken immature, diseased) (wt.) 10.0% Motes (tangled knots of lint) 8.0% Leaves, stems, etc. 70.0% Moisture 10-15.0% CHEMICAL CONSTITUENTS Protein (total nitrogen about 2.3%) 15.00% Fiber 20.00% Phosphorus 00.38% Potassium 00.10% Iron Traces Pesticidal residues (roughly) 250 ppm ______________________________________
These constituents vary, for the most part, with the seasonal dates of harvest, the degree of disease, insect and weed infestations of the fields, weather and general vigor of the crop. However, several independent analyses of the waste or tailings indicate a stable chemical composition which is regulated by the genetics of the cotton plant. A normal clean crop will have a consistently stable composition similar to that given above.
At the present time all horticultural plant growing media, such as potting soil for growing plants, is sterilized by heat or chemical treatment or is formulated from pest free or sterile components, peat, expanded minerals and the like. One of the better examples of this is shown in Cornell University Information Bulletin 43, July 1972 at Pages 1-8.
If a pest bearing seed is planted in this type of media, or if contamination is accidentally introduced into the pest free or sterile media, the introduced pest has no competition and will run wild through the media destroying as it goes.
The utilization of cotton gin waste, or tailings, has been explored by many farmers, ginners and professional people since the invention of the gin. Its value as animal feed is well known except that today it normally contains pesticidal residues which prohibit its use for animal feed.
It is known to be an excellent organic fertilizer except that it contains plant disease causing agents, insects, weed seeds and pesticidal residues detrimental to plant growth. For this reason its movement is restricted by federal and state plant health regulations.
A method of composting gin waste was proposed by Willis in 1954 (Willis, W. H. Composting Cotton Gin Trash, La. Agri. Exp. Sta. Bul. No. 490, 1954) and by Alberson and Hurst, 1964. (Alberson, D. M. and W. M. Hurst, Composting Cotton Gin Waste. 1964. USDA, ARS 42-102, (16 pages, illus.)). Both investigators used the natural process or variations thereof which consisted of stacking the material in a pile, applying water and allowing fermentation to proceed.
My research has shown that to attempt to compost cotton gin waste as described by Willis, and by Alberson and Hurst, resulted in an anaerobic fermentation near the center of the pile which prevented the fermentation from going to completion while the outer several inches of the pile decayed very slowly, providing a cover for flies, other insects and rodents.
Alberson and Hurst and others (Staffeldt, E. E. 1959. Elimination of Verticillium albo-atrum by Composting Cotton Gin Waste, Plant Disease Reporter 43:1150-1152), have shown that composted cotton gin waste destroys the fungus causing verticillium wilt of cotton. However, again it must be emphasized that the natural method of composting as used by Alberson and Hurst, Willis and others, does not include the outer few inches of the compost pile which escapes the heating process. The natural method of composting does not cleanse the mass completely, nor does it comply with Federal requirements.
After repeating the composting processes of Willis and Alberson-Hurst and testing the end products produced by gin wastes from Louisiana, Arkansas and Mississippi, it was concluded that their processes were not sufficiently well controlled to meet the federal regulations of the Animal and Plant Health Inspection Service (APHIS) of the United States Department of Agriculture (USDA). In general, the federal regulations require that noxious weed seeds (of which there are several), dangerous insects (such as the pink boll worm), certain cotton plant diseases which are common to many plants and plant parasitic nematodes (such as root knot and soybean cyst) must not be present in the finished product if it is to be moved from the gin yard site. The original objective of both Willis and Alberson-Hurst was to so compost gin waste that it could be moved back on to the fields and pastures as a soil conditioning mulch and as a fertilizer.
The object of this invention is to provide a process for the conversion of raw gin waste into a type of humus that will not only meet the requirements of the Animal and Plant Health Inspection Service but also be of commercial value to the Horticultural and Biological professions.
A further object of the present invention is to provide a means for promoting growth of trees and shrubs.
Still yet a further object of the present invention is to provide a useful medium having a variety of horticultural uses.
These and other objects of the present invention will be more apparent from the discussion which follows.